The long term objective of this study is to understand the functioning of receptors so as to be able to design new artificial receptors for therapies for diseases in which receptor functions fail or need better timing. To achieve this objective several important steps must be taken and these are the specific aims of this proposal. The first is to understand the mechanism of transmembrane signaling. Tools for this purpose are being developed and applied to the aspartate receptor that can then be applied to more complex receptors. A second aim is to alter the specificity of a receptor so that unnatural compounds can initiate a signaling system. This two fold program is the prologue to the third aim of making chimeric receptors that can be turned on and off by artificial compounds according to the timing of the experimenter. As a model for such systems, the aspartate-insulin chimeric receptor will be studied, in particular its translocation to the desired location, because ultimately we want the receptor in the outer membrane. Finally the signaling pathway for chemotaxis will be explored to see whether it is present in mammalian cells. Because the phosphate groups that are involved in the bacterial signaling pathway are histidine phosphate and carboxyl phosphate in contrast to the serine, threonine and tyrosine phosphates of the known mammalian pathways we will make antibodies against histidine phosphate, identifying the proteins by Western blots and sequencing them. Carboxyl phosphate are less stable but may then be looked for by LiBH 4 reduction and sequencing.